The present invention pertains to laser processing systems. More specifically, the invention relates to an improved laser pipe handling and cutting system.
The use of lasers in the processing of materials has become widespread in the past two to three decades. Among other things, lasers are used to cut pipe, both longitudinally and laterally.
Currently, there are a number of systems that can be used for laser cutting pipe in a longitudinal direction. One type of laser pipe cutting system uses an XY (lateral and longitudinal) table, and a stationary third axis with a rotating chuck. The maximum length of pipe that this laser cutting system can cut is limited to the maximum stroke of its XY table.
Another laser pipe cutting system has an XY table and a stationary third axis with a hollow power chuck and a pipe feeding mechanism. This system with the hollow chuck can accommodate longer lengths of pipe.
Both of these systems have an inherent pipe cutting accuracy deficiency. This is because the laser cutting takes place between two pipe supporting mechanisms, which are remote from the laser pipe cutting head. Since pipe stocks are not perfectly straight, especially when the pipe walls are thin, the pipe is distorted and accurate cutting cannot take place over the whole length of the pipe.
Normally, in laser pipe cutting, the laser beam is directed downwardly perpendicular to the pipe centerline. This is true, except in those cases where there is special angle pipe cutting. The following discussion applies to vertical laser cutting. Because a curved or bent pipe is inherently supported by two pipe supported locations only, the pipe tends to sway from the cutting centerline (a line scribed by the laser cutting head movement along the length of the pipe). This results in untrue or deformed cut patterns, for example, holes cut at one side of the pipe are larger than the holes cut at the other side.
A third laser pipe cutting system, which is dedicated to pipe cutting only, eliminates the XY flat cutting table. In this system, the pipe to be cut is held by a rotating pipe holder with rollers, and is linearly moved and rotated by two motors under a fixed laser pipe cutting head to generate the cutting patterns into the pipe. This system may cut pipes accurately but it loses the versatility of cutting flat materials.
Other common problems with existing laser pipe cutting systems are that hollow power chucks that can accommodate large diameter pipe are very bulky, heavy and expensive. Furthermore, the oversize chuck hole size has small tolerances which confines the machinable pipe diameters to a small range for the particular chuck.
This invention provides a pipe handling system which can transform an XY flat cutting system into a pipe cutting system and maintain very accurate pipe positions for laser, plasma, mechanical or other pipe material processes, even with reasonable distortions in the pipe. The invention also provides a pipe handling system which can accommodate longer pipes, and a large range of pipe diameters. The pipe handling system is simple, lightweight and more economical than conventional pipe handling systems.
The rails can have holes therein to enable cut scraps to pass. The pipe grabbers can have soft pipe contacting linings. The system can include a laser for cutting the pipe.
The invention in one aspect is directed to a pipe handling and XY laser cutting system comprising: (a) a frame; (b) a laser pipe cutting head associated with the XY laser cutting system and its frame; (c) a first carriage for longitudinal travel in relation to the frame, said carriage holding the laser pipe cutting head; (d) a second pipe holding carriage associated with the frame and pipe cutting head carriage, said pipe holding frame carriage having members which hold a pipe at opposite radial locations relative to the cutting head, said carriage being capable of travelling in a longitudinal direction in relation to the frame; (e) a third chuck carriage assembly associated with the pipe holding carriage, capable of longitudinal movement in relation to the frame, said chuck carriage assembly being adapted to engage one end of a pipe and impart rotational movement thereto; and (f) a computer which is associated with the first, second and third carriage assemblies, said computer coordinating longitudinal, rotational pipe movement, and longitudinal position of the second pipe holding carriage in relation to the laser cutting head.
The members which hold the pipe can be moved by air cylinders. The second pipe holding carriage assembly and the third chuck carriage assembly can move on parallel longitudinally extending rails which can be associated with the frame.
A pair of the members holding the pipe can be bearing yokes which can be controlled by air cylinders. The chuck carriage can be driven by a computer controlled motor.
The system can include a pair of chuck carriage stoppers for maintaining pipe in a fixed position while being cut by the laser cutting head. The system can also include a linear actuator system associated with the parallel rails and connected to the control computer by a motor for generating longitudinal movements to the second carriage assembly.
The invention also pertains to a method of cutting pipe which comprises a first pair of pipe grabbers located on a first side of a laser pipe cutting head, a second pair of pipe holders located on a second side of a laser pipe cutting head, a chuck connected to an end of the pipe for imparting rotational movement to the pipe relative to the laser cutting head; and moving the first pipe grabbers and the second pipe holders in association with movement of the laser cutting head along the length of the pipe, and maintaining respective positions on first and second sides of the laser cutting head.
The movements of the first pipe grabber, the second pipe holder, rotational movement of the pipe, and longitudinal movement of the pipe cutting head can be controlled by a computer.
The invention also pertains to an adapter sleeve, which has internal surfaces comprising a plurality of rollers which ride on materials such as rectangular and square pipes or angles. The adapter sleeve has a circular outside surface which is held by the second pair of pipe holders for cutting such materials.
In a specific embodiment, the invention is directed to an XVW axis pipe handling system comprising: (a) a pair of parallel rails arranged in a channel form along an X axis; (b) a linear actuator system associated with the parallel rails and connected to the third axis of a control computer by a motor for generating linear movements in parallel to movements along the X axis; (c) a transfer linkage for transmitting the movement of the linear actuator system to a cutting carriage plate; (d) a cutting carriage plate for mounting thereon carriage brackets and air cylinder adapter brackets; (e) a pair of carriage brackets integral to said cutting carriage plate for mounting track rollers; (f) a plurality of track rollers for said cutting carriage assembly for enabling the carriage assembly to ride on said channel rails; (g) a pair of air cylinder adapter plates for adjusting the gap of a bearing yoke by means of adjusting screws for handling a large range of pipe diameters; (h) a pair of air cylinders, each having thereon a pipe grabber; (i) a pair of air cylinders, each having a bearing yoke with a pair of ball transfer pipe bearings for holding and transporting the pipe; (j) a chuck carriage plate for mounting a pair of carriage brackets and a V motor; (k) a pair of carriage brackets integral to said chuck carriage plate for mounting track rollers; (l) a plurality of track rollers for said chuck carriage assembly to enable the carriage to ride on said channel rails; (m) a pair of chuck carriage stoppers for maintaining pipe in a fixed position while being cut; and (n) a position sensor for detecting a correct pipe and carriage position signal for the control computer.